The present invention relates to an improved coupling arrangement that may be used with conventional railway bogies for the purpose of forming a train of highway trailers.
Highway trailers that can be used on both highways and railways have been known for some time and the economic benefits resulting from the use of trailers that may be used in either a xe2x80x9croadxe2x80x9d mode or a xe2x80x9crailxe2x80x9d mode are well established.
Generally, these types of trailers include retractable wheel assemblies wherein the highway wheels may be retracted and drawn closer to the underside of the trailer. This enables a railway bogie to be placed under the trailer such that when the trailer""s wheels are retracted, the trailer becomes supported by the railway bogie and hence may be transported by rail.
Various forms of interconnection between the trailer and the railway bogie have been proposed, but these have generally involved significant alteration to either the trailer, the railway bogie, or both. In particular, it has been usual for the railway bogie to be placed underneath the rear of a leading trailer to support the weight of that trailer. Connection with the following trailer has usually been effected by directly interconnecting the two trailers.
Whilst this arrangement has been relatively successful, it has required the retractable wheel assembly to be capable of sliding along the underside of the trailer to ensure no interference between the highway wheel assembly of the trailer and the railway bogie. Consequently, there has been a requirement placed upon highway trailers to include extra mechanisms to effect the sliding of the wheel assembly away from the rear of the trailer. This results in increased manufacturing cost of such trailers and a reduction in the pay load of the trailers both in xe2x80x9crailxe2x80x9d and xe2x80x9croadxe2x80x9d mode due to the extra weight of the sliding mechanism.
The requirement for a trailer to include a sliding mechanism for a retractable wheel assembly is avoided in the present invention in that the improved arrangement retains the railway bogie at a sufficient distance from the rear of the leading trailer such that there is no interference between the railway bogie and the wheels when the wheel assembly is retracted. An improved coupler according to the present invention has the benefit of reducing the cost of manufacture of the trailers and the weight of the trailers, which in turn, improves the pay load of hauling the trailers in both the xe2x80x9croadxe2x80x9d and xe2x80x9crailxe2x80x9d mode.
The present invention provides a coupling arrangement for forming a train of highway trailers including;
at least one leading trailer including a rearwardly disposed locating means and a retractable highway wheel assembly;
at least one following trailer including a forwardly disposed locating means and a retractable highway wheel assembly; and
a coupler removably and pivotally mounted upon a railway bogie, the coupler including a forwardly projecting coupling means and a rearwardly disposed coupling means, the forwardly projecting coupling means capable of engagement with the leading trailer""s rearwardly disposed locating means and the rearwardly disposed coupling means capable of engagement with the following trailer""s forwardly disposed locating means;
such that, upon engagement of the respective coupling means with the respective locating means, the forwardly projecting coupling means forms a generally rigid beam from the rear of the leading trailer to the interface between the coupler and the railway bogie, and upon generally vertical retraction of the leading trailer highway wheel assembly to the underside thereof, no interference between the highway wheel assembly and the railway bogie occurs.
The formation of a generally rigid beam from the rear of the trailer to the railway bogie by the forwardly projecting coupling means of the coupler when engaged with the locating means allows the railway bogie to be maintained at a sufficient distance from the rear of the trailer such that there is no interference between the highway wheel assembly and the railway bogie. As a result, the trailer is not required to include any means to slide the highway wheel assembly forward to avoid interference with the railway bogie.
In a preferred form of the present invention, the forwardly projecting coupling means includes a V shaped member generally residing in a horizontal plane, with the rearwardly disposed locating means including a generally vertically aligned pin such that the V shaped member forms a xe2x80x9cgatheringxe2x80x9d mechanism by which the coupling means xe2x80x9cgathersxe2x80x9d the pin and thus locates the forwardly projecting coupling means. It is also preferred that the rearwardly disposed locating means include at least one load bearing surface that will resist a generally vertically downwardly directed force and at least one load bearing surface that will resist a generally vertically upwardly directed force. Preferably, when correctly located, the V shaped member rests upon the at least one load bearing surface resisting generally vertically upwardly directed forces and the at least one load bearing surface resisting generally vertically downwardly directed forces.
It is preferred that the engagement of the forwardly projecting coupling means with the rearwardly disposed locating means occur by way of a forwardly disposed engagement means located at the centre of the V shaped member which is capable of releasable engagement with the pin of the rearwardly disposed locating means, thereby retaining the free ends of the V shaped member in contact with the load bearing surfaces in the rearwardly disposed locating means when the pin is engaged in the forwardly disposed engagement means. Preferably the forwardly disposed engagement means includes a self-latching mechanism that engages the pin as the coupler is urged toward the locating means and the pin travels into the forwardly disposed engagement means at the centre of the V shaped member.
It is also preferred that the rearwardly disposed coupling means be pivotally connected to the coupler, the aixs of rotation residing in a generally horizontal plane thereby enabling angular movement of the coupling means with respect to the following trailer. Preferably, the rearwardly disposed coupling means also includes a V shaped member generally residing in a horizontal plane, and the forwardly disposed locating means on the following trailer includes a generally vertically aligned pin similarly forming a gathering mechanism by which the coupling means gathers the locating means pin.
It is also preferred that the engagement of the rearwardly disposed coupling means with the forwardly disposed locating means occur by way of a rearwardly disposed engagement means located at the centre of the rearwardly disposed V shaped member which engages the locating means pin. For the forwardly disposed locating means, it is preferred that the pin be retractable. In this respect, for convenience and safety reasons, it is preferred that the pin be retracted upwards to an inoperative position and extended downward to an operative position.
The generally V shaped member and the pin of either the forward or rearward coupling mechanisms assists in overcoming difficulties that have been experienced with prior coupling arrangements in relation to coupling the railway bogie with the trailer. Some prior arrangements have included converging side walls in the coupling mechanism of both the bogie and the trailer, effectively forming a mating male-female connection. Disadvantageously, this type of arrangement increases the friction associated with coupling the mechanism and hence increases the difficulty in obtaining a secure coupling between the bogie and the trailer. In the preferred embodiment, the only frictional force resisting the passage of the pin to the centre of the member is that due to the contact between the pin and the inner side wall of the V shaped member.
It is preferable that the pin engaging means for either or both of the forwardly and rearwardly projecting coupling means include a generally U shaped jaw that is pivotally connected to the coupler and adapted to receive the respective locating means pin such that as the pin is introduced into the mouth of the jaw and continues toward the centre of the V shaped member, the jaw pivots and one arm of the jaw locates behind the pin with respect to the pin""s direction of travel such that the arms of the U shaped jaw then reside generally transverse to the direction of the arms of the V shaped member. It is further preferred that a generally laterally disposed locking wedge be provided to wedge the jaw into an engaged position once the engagement means has fully received the pin. Once the locking wedge is urged into a position corresponding to engagement of the pin, it prevents the jaw from pivoting and hence prevents the release of the locating means pin by the jaw. Preferably, the locking wedge is operated by linkages that are connected to a handle disposed on the exterior of the coupler, thereby enabling operation by hand. In a particularly preferred embodiment, the locking wedge is biased such that it is urged into an engaging position once the pin is fully received into the locking jaw with one arm thereof located behind the pin. In this embodiment, the locking wedge is urged against its bias and withdrawn from its engaging position by the operation of linkages. Preferably, a retention means is provided to retain the locking wedge in its withdrawn position against its bias, the retention means being released upon the reception of the pin into the pivotally connected jaw.
In prior art arrangements, some problems have been experienced with the integrity of coupling between the bogie and the trailer. In some arrangements, a pin has been used to engage the coupling mechanism. However, the pin has generally been used to lock the coupling mechanism by forcing the pin generally upwardly such that it resides within overlapping apertures thereby locking the apertured members together. This type of arrangement has proven not to be fail safe in that gravity and other forces acting upon the pin during travel have in some instances caused the pin to drop out of its locking position. In rare instances, this has resulted in a complete disengagement of a railway bogie and trailer thereby causing an extreme safety risk. The inclusion of a generally laterally disposed locking wedge assists in overcoming this difficulty.
In a particularly preferred embodiment, the pins of either or both of the locating means includes a generally radially outwardly directed flange that acts to restrict generally vertical movement of the pin once it is engaged in the respective coupler engagement means. In a particularly preferred embodiment, the pin includes a portion that is of a reduced diameter in the region at which it is engaged by the pivotally mounted locking jaw. Accordingly, the pin surface residing between the two portions of varying diameter above and below the arms of the locking jaw act to restrict generally vertical movement of the pin and prevents removal of the pin from the coupler when it is engaged by the engagement means.
The coupler is removably mountable upon a conventional railway bogie, and is preferably dimensioned such that the forks of a forklift may be located on the underside of the coupler for mounting and demounting the coupler to/from the bogie.
The present invention also provides a coupler suitable for use with the invention including a forwardly projecting coupling means and a rearwardly disposed coupling means.
Preferably the forwardly projecting coupling means includes a generally V shaped member residing in a generally horizontal plane. Additionally, it is preferred that the forwardly projecting coupling means include a forwardly disposed engagement means residing between the arms of the generally V shaped member.
It is further preferred that the forwardly disposed engagement means of the coupler include a generally U shaped jaw pivotally connected to the coupler. It is also preferred that when not in use, the generally U shaped jaw of the forwardly projecting coupling means be biased to a position such that the arms of the U shaped jaw are generally aligned with the arms of the generally V shaped member.
The forwardly projecting engagement means of the coupler also preferably includes a locking means whereupon pivotal movement of the generally U shaped jaw to a position where the arms thereof are generally transverse to the arms of the V shaped member, the locking means is capable of being urged toward the U shaped jaw and abut a portion thereof thereby retaining the U shaped jaw in a locked position. In a particularly preferred embodiment, the locking means of the coupler includes a wedge and additionally the wedge is biased to a position corresponding to the locked position of the U shaped jaw.
In the instance of the forwardly projecting engagement means of the coupler including a biased locking wedge, a retention means may be provided to retain the biased locking wedge in a position corresponding to an unlocked position of the U shaped jaw. In this particular embodiment, the retention means may be released upon pivotal movement of the U shaped jaw thereby enabling the locking wedge to be urged into a position corresponding to the locked position of the U shaped jaw.
In a particularly preferred embodiment, the locking means may be operated manually by way of a linkage. This enables operators of the coupler to manually activate or deactivate the locking means by way the linkage. It is also preferable that the locking means reside in a generally horizontal plane.
Preferably, the coupler also includes a rearwardly disposed coupling means pivotally connected to the coupler with the axis of pivot residing in a generally horizontal plane thereby enabling angular movement of the rearwardly disposed coupling means.
Additionally, it is preferred that the rearwardly disposed coupling means include a generally V shaped member residing in a generally horizontal plane. It is further preferred that the rearwardly disposed coupling means include a rearwardly disposed engagement means residing between the arms of the generally V shaped member.
Further, the rearwardly disposed engagement means may include a generally U shaped jaw pivotally connected to the coupler. In addition, when not in use, it is preferred that the generally U shaped jaw of the rearwardly disposed engagement means be biased to a position such that the arms of the U shaped jaw are generally aligned with the arms of the generally V shaped member. It is also preferable that the rearwardly disposed engagement means include a locking means whereupon pivotal movement of the rearwardly disposed generally U shaped jaw to a position where the arms thereof are generally transverse to the arms of the rearwardly disposed generally V shaped member, the locking means is capable of being urged toward the generally U shaped jaw and abut a portion thereof thereby retaining the U shaped jaw in a locked position.
In an embodiment where the rearwardly disposed engagement means includes a locking means, it is preferable that the locking means includes a wedge. It is also preferred that such a wedge be biased to a position corresponding to the locked position of the rearwardly disposed generally U shaped jaw.
Further, the rearwardly disposed engagement means may include a rearwardly disposed retention means to retain the biased locking wedge in a position corresponding to an unlocked position of the rearwardly disposed generally U shaped jaw. In a particularly preferred embodiment the retention means is released upon pivotal movement of the U shaped jaw thereby enabling the locking wedge to be urged into a position corresponding to the locked position of the rearwardly disposed generally U shaped jaw.